CurtZHP

Member Since 07 Jun 2010
Offline Last Active Jul 25 2016 09:05 AM
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Posts I've Made

In Topic: D-75 Amp -- Suspected fault in IOC

06 July 2016 - 12:24 PM

Found the problem, after I replaced D1.  Was still seeing excessive voltage on that rail.  Upon closer inspection with a magnifying glass, there was a hairline separation in the trace between R2 and D2.  So the diode was effectively out of the circuit.  Used a thin piece of wire to reinforce that trace, and all's well!

In Topic: D-75 Amp -- Suspected fault in IOC

06 July 2016 - 08:30 AM

OK.
Was able to at least check voltages.  +/- 30 rails are healthy.  Measured +/- 10V rails at the IC's.  +10 is good, but -10 rail is reading around -25V!

D1 bad??

In Topic: D-75 Amp -- Suspected fault in IOC

06 July 2016 - 07:56 AM

Finally got this thing on the bench!  (Busy...busy...busy....)
I have the schematic, but I'm having a little trouble locating where the supply voltage gets regulated down to +/- 10VDC.  I can see the +/- 30VDC off the main supply.

Also, my pdf of the service manual doesn't have a very clear image of the main pcb.  Any idea where I can find one?

In Topic: D-75 Amp -- Suspected fault in IOC

31 May 2016 - 08:06 PM

I'll give that a shot.  Thanks!